Atomic Structures

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CHEMICAL BOND

luonut Szeru Tan

NAfME

luonut Keith Kothman

Extrinsic Factors

luonut Marco Bertolini

Chemistry Chemistry is ultimately the study of matter including how it behaves and . Additionally in this unit we talked about how to describe properties and changes using diagrams and nomenclature, and equations.

luonut Ragubavan Sathurtheha

Alkynes

Alkanes but with triple bond between carbon atoms.

• Unsaturated: Doesn't have max hydrogen atoms per carbon atom
• 1 sigma bond, 2 pi bonds
• Bond Order 3

Ex. C₂H₂

Alkenes

Alkanes but have double bonds between carbon atoms.

• Unsaturated: Doesn't have max hydrogen atoms per carbon atom
• 1 sigma bond, 1 pi bond
• Bond Order 2

Ex. C₂H₄

Solutions

Alkanes

Saturated compound with carbon atoms + multiple hydrogen atoms.

• Saturated: Max hydrogen atoms (3) per carbon atom

General formula: C_nH_2n+2

No double bonds between carbon atoms.

• 1 sigma bond
• Bond Order 1

Decane

C₁₀H₂₂

Nonane

C₉H₂₀

Octane

C₈H₁₈

Heptane

C₇H₁₆

Hexane

C₆H₁₄

Pentane

C₅H₁₂

Butane

C₄H₁₀

Propane

C₃H₈

Ethane

C₂H₆

Methane

CH₄

Concentration

Bascitity

pH >7

• Higher concentration of hydroxide ions in solution
• 10x the concentration of OH- per level of pH
• Dissociates in water to form OH- and M+ ions

*Strength of base refers to its dissociation ability rather than concentration.

Strong Base: MOH --> M + OH

Ex. LiOH --> Li + OH

• All alkali bases are strong
• Dissociates completely
• High conductivity (because of ions)

Weak Base: B + H2O --> BH + OH

Ex. NH3 + H2O --> NH4 + OH

• Doesn't dissociate completely
• Slight conductivity (not as much ions)

Acidity

pH <7

• Higher concentration of hydronium ions in solution
• 10x the concentration of H+ per level of pH
• Ionizes in water to form H+ and non-metal ions

*Strength of acid refers to its ionization ability rather than concentration.

Strong Acids: HA + H2O --> H3O + A-

Ex. HCl + H2O --> H3O + Cl-

• All molecules ionize
• High conductivity (because of ions)

Weak Acid: HA + H2O --> H3O + A-

Ex. HF + H2O --> H3O + F- (only some)

• Only some molecules ionize
• Slight conductivity (less ions)

Moles

% Composition

Hydrate Formula

Molecular Formula

Empirical Formula

Types of Reactions

Double Displacement

Neutralization

Forms a gas

NH4 + OH

Ionic Compound + NH3 + H2O

HCO3

Acid + MCO3 --> Ionic Compound + H2O + CO2

Precipitation Reactions

Combustion

Complete: HC + O2 --> H2O + CO2

• When sufficient oxygen is present

Incomplete: HC + O2 --> C + CO + CO2 + H2O

• When insufficient oxygen is present

Other types: element + O2 --> Element oxide

• Synthesis reactions with oxygen can be classified as combustion if light and heat is produced (exothermic)

Single Displacement

Metal swap H from acid

Metal swap Metal

Halogen swap halogen

Metal swap Water

Synthesis/decomp

Bicarbonate

MHCO3 --> MCO3 + CO2 + H2O

Binary Compound

Element + Element

Bases

MOH + H2O

Acid

Nonmetal Oxide + H2O

Carbonates

MCO3 --> MO + CO2

Chlorates

MClO --> MCl + O2

Nitrates

MNO3 --> MNO2 + O2

Types of Bonds

Covalent/Molecular

Atoms bond through shared electrons. Covalent/molecular refers to the bond within a molecule.

IMFS

• Forces which hold molecules together in a structure
• Is broken when changing states or dissolving

H-Bonds

LD

Dipole-dipole

Nonpolar

0-0.5 EN

• Molecules held together through LD IMFS
• These seperate when boiled, dissolved, or melted

Properties:

• Lowest melting/boiling points
• Dissolves in nonpolar solvents, insoluble in polar solvents
• Weakest bonds

Polar

0.5-1.7 EN

• Anything that's neutral overall but has charge seperation
• Molecules held together through dipole-dipole or H-bond IMFS
• These seperate when dissolved, boiled, or melted

Properties:

• Generally high melting/boiling points
• Stronger bonds than nonpolar molecules
• Soluble in polar solvents, insoluble in nonpolar

Ionic

1.7+ EN

• Has no IMFS
• Held together in crystal structure in an equal ratio indictated by subscripts in formula

Properties:

• Very strong bonds, requires lots of energy to break them apart into different states
• High melting and boiling points
• Generally soluble in water through dissociation
• Cations bond to oxygen while anions bond to hydrogen

Atomic Structures

Isotopic Abundance

% of a given isotope in nature out of other isotopes of the same element.

Avg Atomic Mass

Avg. mass of all isotopes of a given element.

= (%abundance x amu) + (%abundance x amu)

Radioisotopes

Isotopes that have unstable nuclei and undergo radioactive decay.

Unstable nuclei: When repulsive-electric force of protons is not balanced with the attractive force of neutrons (too many neutrons).

Theories of the atom

Periodic Trends

Electronegativity

The relative ability of an atom to attract electrons in when bonded in a molecule

Electron Affinity

Energy released when electrons are added

Atomic Radius

Distance between nucleus and outermost electrons

Ionization Energy

Energy needed to remove electrons